The mammalian heart is an organ made up of four muscular chambers that function together to pump blood throughout the body. Each of the four chambers has an associated downstream one-way valve made up of movable, coapting leaflets or cusps which cooperate to prevent the backward flow of blood, or regurgitation, into their respective chambers. Two such heart valves, the aortic and pulmonary valves, also commonly known as the semilunar valves, are characterized by three leaflets or cusps 91. The aortic valve leaflets 91 are attached within the aortic root 90, usually to a tri-scalloped or triple scalloped line of collagenous, fibrous tissue generally referred to as the valve annulus 92. As such, a three-pointed crown-like structure serves to support the aortic valve cusps or leaflets 91. The U-shaped convex lower edges of each leaflet are attached to, and suspended from, the base 97 of the aortic root 90, with the upper free edges or margins 93 of each leaflet being free to move and project into the lumen of the aorta 99. Two adjacent leaflets approach one another at one of the three points of said crown-like structure to define a commissure 95 of the aortic valve. Behind each leaflet 91, the aortic vessel wall bulges outward, forming a pouch-like dilatation known as the sinus of Valsalva 98. In the region located slightly above the level of the commissures 95, the aortic root 90 creating the sinuses of Valsalva 98 merges into the substantially tubular portion of the ascending aorta 99 at a substantially planar transition zone commonly known as the sinotubular junction (STJ) 100. The aortic root 90 houses the aortic valve structures and generally includes the portion of the native aortic conduit extending from the left ventricular outflow tract (LVOT) to the portion of ascending aorta 99 slightly above the sinotubular junction (STJ). Typically, aortic root reconstructions or interventions usually involve the aortic valve, while ascending aorta interventions usually exclude the aortic valve and involve the native aortic conduit located generally downstream of the sinotubular junction. In some patients, one or two of the native valve cusps may be congenitally fused and a bicuspid or, more rarely, a unicuspid aortic valve may present.
Aortic root dilation is one of the most common causes of aortic valve incompetence in North America. Prevalence of surgical corrections for this pathology has increased considerably during the last two decades. There are a variety of surgical corrections (for example the Reimplantation technique popularized by David, or the Remodelling technique popularized by Yacoub) that have been developed over the years to surgically repair an aortic valve or reconstruct the aortic root portion of the ascending aorta. In most surgeries, especially conservative aortic valve surgery which restores valve competence in regurgitant aortic valves having occurred from a dilatation of the aortic root or a retraction of valve cusps, surgeons must replace a portion of the patient's native aorta which is dilated, aneurysmal or pre-aneurysmal with a prosthetic vascular conduit. Typically, the native sinuses of Valsalva and a portion of the ascending aorta are resected leaving behind a scalloped native aortic root 89. Said resected aortic tissue is then replaced by sewing in a new prosthetic vascular conduit.
Current vascular conduits are available in a variety of diameters and lengths to cater to the variations in patient anatomy, or surgeon preference. Such conduits are available as tubular structures made from woven or knit polyester yarn, PET, or also available in ePTFE. These known tubular structures have terminal ends that terminate square or flat or as a plane transverse to the centerline or longitudinal axis of the tubular structure. Consequently, during the surgical procedure, the surgeon must tailor the terminal end of the prosthetic vascular conduit with scallops, tongues or fingers to in order to approximate the aortic valve annulus (or the fringe of tissue 913 above the aortic annulus) which remains of the aortic root after the aneurysmal native sinuses of Valsalva have been resected. In cases of tricuspid aortic valves, the prosthetic graft must be fashioned with three such scallops or tongues. In the hands of inexperienced surgeons, it is challenging to fashion a graft with three such tongues, equally spaced and of similar heights and circumferential width, especially during the surgical procedure when time is of the essence, and when such conventional prosthetic aortic conduits do not have demarcation lines equally spaced apart to guide the surgeon in making three equally spaced tongues (for use in a tricuspid aortic root reconstruction) or in making two equally spaced tongues (for use in a bicuspid aortic root reconstruction).
Accordingly, there exists a need for a prosthetic vascular conduit or aortic graft with pre-shaped or pre-cut terminal ends, produced at time of fabrication of the aortic graft to avoid surgeon having to fashion such conduit ends with two tongues to mate or comply with the scalloped aortic root of a bicuspid aortic valve or with three tongues for a tricuspid aortic valve, during the course of the surgical procedure. Such a precut prosthetic graft or conduit advantageously prepared and available to the surgeon as a sterile implant in various sizes, before the surgical procedure, would greatly facilitate the implantation of the replacement aortic conduit during surgery. As well, consistency in the size and shape of the prefabricated tongues would minimize unwanted variability and tend to improve surgical outcome.
Prosthetic aortic conduits are provided sterile and in a variety of different sizes. As such, a hospital must stock the entire range of sizes available in order to cater to whatever patient anatomy presents during surgery. To exploit the benefits of a prefabricated scalloped conduit and to limit the inventory of different sizes and configurations of aortic conduits that a hospital must stock in sterile inventory, it is advantageous to have an aortic conduit having a first terminal end fashioned with two scallops or tongues in the event that a patient with a bicuspid valve presents, and a second opposed terminal end fashioned with three scallops or tongues in the event that a patient with a tricuspid valve presents. Such a conduit with two scalloped terminal ends would improve the logistics associated with stocking sterile implants, reordering and traceability of same, since fewer graft configurations must be managed within the hospital's inventory pool. A solitary graft chosen based on its tubular diameter can be selected for the surgical case, and then depending on the patient's specific anatomy of aortic valve, either the tri-scalloped or bi-scalloped end of the graft implanted to the aortic root through a proximal anastomosis, while the opposite end of the graft is cut away from the tubular portion of the conduit since it is not appropriate for that patient's anatomy. Moreover, the cutting away of the not-needed scalloped end along a length of tubular portion of the graft, prepares same for the distal anastomosis to the native ascending aorta.
It is thus a first object of the present invention to provide a prosthetic aortic conduit having a first terminal end configured and sized with three tongues to comply or mate with a scalloped tricuspid aortic root, and a second terminal end configured and sized with two tongues to comply or mate with a scalloped bicuspid aortic root.
It is a further object to provide a prosthetic aortic conduit having pre-shaped scalloped first and second terminal ends, provided sterile, in order to minimize the inventory of different graft diameter sizes to be stocked at the hospital to cater to whatever patient anatomy presents itself during the course of a surgery.
It is a further object to provide a prosthetic aortic conduit wherein said tongues have reinforced free margins along the zone where the proximal anastomosis suture line is placed between the resected native aortic root and the scalloped terminal end of the prosthetic aortic graft.
It is a further object of the present invention to provide a prosthetic aortic conduit wherein said tongues have free margins configured with sealing members or hydrogel members or improved sealing interfaces or surface treatments in order to promote or enhance the hemostasis of the suture line between the prosthetic graft and the native scalloped aortic root.
It is a further object of the present invention to provide a prosthetic aortic conduit wherein said tongues have free margins impregnated or configured with a biological or tissue glue to help promote adhesion of the prosthetic graft to the native scalloped aortic root.
It is a further object of the present invention to provide a prosthetic aortic conduit wherein said tongues have free margins treated with a pharmacological agent effective in promoting with tissue-ingrowth into the aortic prosthesis, or treated with a bioreaction controlling agent effective in controlling the pannus growth between the native and prosthetic aortic graft.
It is also a further advantage to provide a prosthetic aortic conduit for use in conservative aortic valve surgeries where the native valve cusps are preserved, but there exists the need to replace aneurysmal aortic root tissue, such as the Sinuses of Valsalva, or an aneurysmal ascending aorta with a tailored prosthetic conduit.